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Cumulative Preferred Stock (Narrative) (Details) - $ / shares | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2013
First Preferred Shares [Member] |  |
Class of Stock [Line Items] |  |
Preferred Stock Dividend Preference Or Restrictions | First Preferred Shares are neither redeemable at the option of the shareholder nor have a mandatory redemption date. They are classified as equity and the associated dividends is deducted on the Consolidated Statements of Income before arriving at “Net earnings attributable to common shareholders” and is shown on the Consolidated Statement of Equity as a deduction from retained earnings. The First Preferred Shares of each series rank on a parity with the First Preferred Shares of every other series and are entitled to a preference over the Second Preferred Shares, the Common Shares, and any other shares ranking junior to the First Preferred Shares with respect to the payment of dividends and the distribution of the remaining property and assets or return of capital of the Company in the liquidation, dissolution or wind-up, whether voluntary or involuntary. In the event the Company fails to pay, in aggregate, eight quarterly dividends on any series of the First Preferred Shares, the holders of the First Preferred Shares, for only so long as the dividends remain in arrears, will be entitled to attend any meeting of shareholders of the Company at which directors are to be elected and to vote for the election of two directors out of the total number of directors elected at any such meeting. |
Series A Preferred Stock [Member] |  |
Class of Stock [Line Items] |  |
Convertible Preferred Stock Terms Of Conversion | Series B |
Annual Dividend Per Share | $ 0.6388 |
Outstanding share redemption price per share | $ 25 |
Preferred stock, dividend rate, percentage | 4.40% |
Series A Preferred Stock [Member] | Minimum [Member] |  |
Class of Stock [Line Items] |  |
Preferred stock, dividend rate, percentage | 1.84% |
Series C Preferred Stock [Member] |  |
Class of Stock [Line Items] |  |
Convertible Preferred Stock Terms Of Conversion | Series D |
Annual Dividend Per Share | $ 1.1802 | $ 1.025
Outstanding share redemption price per share | $ 25 |
Preferred stock, dividend rate, percentage | 4.10% |
Series C Preferred Stock [Member] | Minimum [Member] |  |
Class of Stock [Line Items] |  |
Preferred stock, dividend rate, percentage | 2.65% |
Series F Preferred Stock [Member] |  |
Class of Stock [Line Items] |  |
Convertible Preferred Stock Terms Of Conversion | Series G |
Annual Dividend Per Share | $ 1.0625 |
Outstanding share redemption price per share | $ 25 |
Preferred stock, dividend rate, percentage | 4.25% |
Series F Preferred Stock [Member] | Minimum [Member] |  |
Class of Stock [Line Items] |  |
Preferred stock, dividend rate, percentage | 2.63% |
Series B Preferred Stock [Member] |  |
Class of Stock [Line Items] |  |
Convertible Preferred Stock Terms Of Conversion | Series A |
Outstanding share redemption price per share | $ 25 |
Preferred stock, dividend rate, percentage | 2.393% |
Series B Preferred Stock [Member] | Minimum [Member] |  |
Class of Stock [Line Items] |  |
Preferred stock, dividend rate, percentage | 1.84% |
Series H Preferred Stock [Member} |  |
Class of Stock [Line Items] |  |
Convertible Preferred Stock Terms Of Conversion | Series I |
Annual Dividend Per Share | $ 1.225 |
Outstanding share redemption price per share | $ 25 |
Preferred stock, dividend rate, percentage | 4.90% |
Series H Preferred Stock [Member} | Minimum [Member] |  |
Class of Stock [Line Items] |  |
Preferred stock, dividend rate, percentage | 4.90% |
Series I Preferred Stock [Member] |  |
Class of Stock [Line Items] |  |
Preferred Stock Dividend Payment Rate Variable | Government of Treasury Bill Rate on the applicable reset date |
Series I Preferred Stock [Member] | Minimum [Member] |  |
Class of Stock [Line Items] |  |
Preferred stock, dividend rate, percentage | 2.54% |
Perpetual fixed rate Series E Preferred Stock [Member] |  |
Class of Stock [Line Items] |  |
Annual Dividend Per Share | $ 1.125 |
Outstanding share redemption price per share | 26 |
Preferred Stock, Redemption Price, Annual Decrease | 0.25 |
Preferred Stock, Redemption Price, Annual Decrease, After Year Five | $ 25 |
Preferred stock, dividend rate, percentage | 4.50% |

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- Definition Specific terms relevant to convertibility. Includes class of preferred stock and number of shares convertible into, exercise (or conversion) price or rates, dates relevant to conversion timing and events relevant to conversion. Describe also any beneficial conversion features. where convertible preferred stock with a nondetachable conversion feature is in-the-money at commitment date. For contingently convertible preferred stock, discuss the circumstances of the contingency, including the events or changes in circumstance that would cause the contingency to be met and any of the significant features necessary to understand the conversion rights and the timing of those rights. Include also an events or changes in circumstance, if any, that could adjust or change the contingency, conversion price, or number of shares, including significant terms of those changes. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(27)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02(28)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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